APU Flashcards
On ground, APU provides bleed air for
Engine starting and air conditioning system
APU air intake flap opens when the APU MASTER pb switch is ON/R
APU bleed valve automatically closed above 25,000 ft climbing and reopens at 23,000 ft when descending
APU shutdown can be initiated by GND crew using
APU SHUT OFF on external interphone panel or the refueling / de-fueling panel
APU Master pb sw ON/R –illuminates
blue ON/R
When APU START pb sw is ON, blue light illuminates when
Intake flap is completely open, APU starter is engaged.
APU GND operation
14,600 ft
Bleed / electrical up to
22,500 ft
Electrical power up to
41,450 ft
Bleed air extraction 1 pack – 22,500 ft / 2 packs
17,500 ft
APU battery restart limit
25,000 ft
Air bleed extraction for wing anti ice is
Not permitted
After 3 consecutive APU start attemps,
60 min cooling
APU Max N
107%
APU Max EGT
650 ºC while APU running
MAX APU EGT
1,250ºC
LOW OIL LEVEL ECAM on ECAM APU page – APU can be
Started and maintenance within next 15 hours
Max rotor speed N for APU is
107%
After APU started, APU ECAM remains
15 seconds
On APU ECAM page, bleed air pressure display is replaced by
Amber xxx when ADIRS 1 is not available or selected OFF
LOW OIL LEVEL on APU ECAM when
ECB detects low APU oil level and aircraft on GND, APU not running
Walk around – check APU
Access door, air intake, exhaust
APU normally started aircraft at
Gate supplied by external power
APU start sequence completed ECAM APU page AVAIL appears. APU START pb sw ON extinguishes
And AVAIL illuminates
APU running, external power A or B may be kept ON to
Reduce APU load, especially in hot conditions.
APU emergency shutdown when pressed
APU FIRE pb, APU SHUTOFF pb, APU EMER SHUT DOWN pb
APU automatic shutdown:
Start abort, low oil pressure, high oil temperature
APU fire detected on GND,
APU automatic shut down, agent discharge
